Nowadays, electric vehicles start to replace fossil fuel vehicles. In addition, electric vehicles are gradually applied to the public transportation field. One of many feasible methods of implementing the electric-powered system to the public transportation vehicles is to use swappable battery packs and battery swap stations. For example, the battery packs in the battery swap stations are fully charged at first. When the battery pack of an electric bus is nearly depleted, the electric bus stops at a specified battery swap station. Then, the depleted battery pack of the electric bus and the fully-charged battery pack of the battery swap station are exchanged with each other within 5 to 10 minutes. Consequently, the electric bus can acquire sufficient electric power from the fully-charged battery pack to be continuously driven.
In practice, each battery cell in a battery module of the battery pack degrades at different rates during its service time. Moreover, the capacity of each battery module inevitably deteriorates after the third year of the service time. The deterioration of the battery capacity causes a mileage reduction up to about thirty percent. For allowing the battery pack to discharge electricity uniformly, all battery modules of the battery pack have to be kept at a similar capacity range and at a similar internal resistance range. Regardless of the age of battery module, any degraded battery module of the battery pack needs to be replaced with the new one. For realizing the status of the battery module, it is necessary for the battery pack provider to frequently test the battery module. After the capacity of the battery module is predicted and the status of the battery pack is realized, the battery pack provider can provide good service to the electric bus agency and the electric taxi agency.
Conventionally, the battery module is retested in a specialized facility. After the battery module is retested, it is necessary to download and transfer the operation data, the SOH (state of health) data, the SOC (state of charge) and the usage histories of the substituted battery module or the newly-installed battery module from a battery pack management unit or an electronic control unit (ECU). As known, this process is time-consuming and costly to the battery pack provider.
Moreover, when a fault event of the battery module occurs, a surge current generates. The surge current may destroy the battery cell and damage the battery management unit. Under this circumstance, the operation data of the battery module stored in the battery management unit are unrecoverable. That is, the user of the battery module cannot acquire the operation data of the battery module.
Therefore, there is a need of providing a battery management apparatus to overcome the drawbacks of the conventional technology such as the damage of the battery management unit from surge current, the unrecoverable operation data of the battery module and the time-consuming process of acquiring the state of the battery module.